Writing an Augeas lens - mongodb

Question

I need to edit one line in /etc/mongodb.conf
auth = true
Augeas has a mongo lens, however it only works on augeas > 1.0
I am completely stuck on augeas 0.9 because it is the latest version in the epel repo, and I can not compile augeas from github.
As a work around, I'm trying to write my own augeas lens that will work on augeas 0.9
What I have so far is this
module Spencer =
autoload xfm
let entry = key /[a-z]+/ . del /[ \t]*=[ \t]*/ "=" . store /[a-z]+/
let lns = [ entry . del "\n" "\n" ] *
test lns get "auth = false\nfoo = bar\n" = ?
let filter = incl "/etc/mongodb.conf"
let xfm = transform lns filter
When I try and use the puppet type to apply the lens to /etc/mongodb.conf, I get an error "Iterated lens matched less than it should".
puppet apply augmongo.pp --debug --verbose --summarize
Info: Applying configuration version '1385024927'
Debug: Augeas[auth-mongo](provider=augeas): Opening augeas with root /, lens path , flags 64
Debug: Augeas[auth-mongo](provider=augeas): Augeas version 0.9.0 is installed
Test result: /usr/share/augeas/lenses/dist/spencer.aug:8.0-.44:
{ "auth" = "false" }
{ "foo" = "bar" }
Debug: Augeas[auth-mongo](provider=augeas): Will attempt to save and only run if files changed
Debug: Augeas[auth-mongo](provider=augeas): sending command 'set' with params ["/files/etc/mongodb.conf/auth", "true"]
Debug: Augeas[auth-mongo](provider=augeas): Put failed on one or more files, output from /augeas//error:
Debug: Augeas[auth-mongo](provider=augeas): /augeas/files/etc/mongodb.conf/error = put_failed
Debug: Augeas[auth-mongo](provider=augeas): /augeas/files/etc/mongodb.conf/error/pos = 1
Debug: Augeas[auth-mongo](provider=augeas): /augeas/files/etc/mongodb.conf/error/lens = /usr/share/augeas/lenses/dist/spencer.aug:6.10-.37:
Debug: Augeas[auth-mongo](provider=augeas): /augeas/files/etc/mongodb.conf/error/message = Iterated lens matched less than it should
Debug: Augeas[auth-mongo](provider=augeas): Closed the augeas connection
Error: /Stage[main]/Augmongo/Augeas[auth-mongo]: Could not evaluate: Save failed with return code false, see debug
Debug: Finishing transaction 69857417180740
Debug: Storing state
Debug: Stored state in 0.13 seconds
What is wrong with the lens?
How can I test a lens from the command line and take puppet out of the equation?

Answer 1

RHEL 6.4 just upgraded to Augeas 1.0. See https://rhn.redhat.com/errata/RHSA-2013-1537.html.
You should be able to rebuild the packages, or wait for CentOS to do that for you.

Answer 2

I have had similar issues with augeas & puppet. Applying changes seemed to end with the error Could not evaluate: Save failed with return code false every time. This turned out to be an syntax issue. I had:
set spec[user = '%somegroup']/host_group/command/tag NOPASSWD
(notice two empty space between tag and NOPASSWD).
When I tried the same command with one empty space, the issue was solved.
Looking into the template/lens (spencer.aug, line 6.10-.37) might offer some clue at what went wrong.